Oropharyngeal infection is an important component of Epstein-Barry virus (EBV) pathogenesis. Oral transmission is the most common mechanism for acquiring primary EBV infection, and persistent, lifelong oropharyngeal infection is ubiquitous in the adult population. EBV infection in the upper aerodigestive tract is also associated with nasopharyngeal and gastric carcinomas in immunocompetent hosts and oral hairy leukoplakia in immunosuppressed hosts. However, the cell types naturally infected by EBV, the role of lytic EBV replication, and the effect of immunosuppression on the pathogenesis of acute and persistent infection in the upper aerodigestive tract remain poorly understood. We will test the hypothesis that epithelial cells are naturally infected during acute and persistent EBV infection. We also hypothesize that lytic viral replication in epithelial cells is an important mechanism for viral amplification during primary infection. Alternatively, oral transmission and primary infection may be mediated by direct infection of B cells trafficking near the oropharyngeal mucosa with virus amplification resulting from proliferation of latently infected B cells. Two models of high oropharyngeal viral loads in immunosuppressed hosts will also be explored: i) reactivation of viral replication after immunosuppression in a subset of naturally infected epithelial cells, or ii) spread of virus infection after imnmunosuppression from B cells to epithelial cells not normally infected in immunocompetent hosts. We have developed an animal model using a closely related herpesvirus in the same lymphocryptovirus (LCV) genera as EBV that naturally infects rhesus macaques. The rhesus LCV has a high degree of biologic and molecular similarity to EBV, and experimental infection in humans. We have cloned and fully sequenced the rhesus LCV genome and have developed a genetic system for mutating the virus as an artificial bacterial chromosome. We will use the rhesus animal model to study the following aspects of LCV pathogenesis in macaques and humans. Specific Aim #1: Identify the natural oropharyngeal targets for acute and persistent rhesus LCV infection after oral inoculation. Specific Aim #2: Identify oropharyngeal reservoirs of EBV infection in persistently infected immunocompetent and immunosuppressed humans by translation of animal model results to humans. Specific Aim 3: Test whether LCV oral transmission requires oropharyngeal epithelial contact or whether transmission can be mediated through the gastric mucosa. Test whether achlorhydria can enhance the efficiency of LCV infection through the gastric mucosa. Specific Aim #4. Test the role of viral replication in the pathogenesis of acute and persistent LCV infection after inoculation.